The invention relates to measuring by acoustics, lengths and cross sections in a patient""s right and left nose cavity which are mutually separated by the nose separation (septum nasi), in the cavity behind the nose separation (epipharynx) and in the throat (oropharynx); the invention further relates to detecting the opening of the Eustachian tubes.
Acoustic rhinometry (Reflectometry) is, e.g. known from U.S. Pat. No. 4,326,416 (Fredberg). The method and apparatus is further described by Ole Hilberg, Ole Finn Petersen and A. C. Jackson in 1988. An instrument for acoustic rhinometry is produced by the firm Hood Labs in Boston from the beginning of the 1990""s and by the Scottish firm GM instruments since 1993. The known methods and apparatuses comprise both the use of continuous and discontinuous signals.
An overview of acoustic rhinometry and known examination methods is found in xe2x80x9cAkustisk rhinometrixe2x80x9d by Per Djupesland, Tidsskrift for Den Norske Laegeforening, no. 26 1996, 116, pp. 3111-3114.
In acoustic rhinometry (reflectometry) a sound signal is generated and sent into the nose cavities through an adapted connecting piece. Part of the sound signal is reflected from the cavities in the nose and the throat, and by data analysis of the differences between the ingoing and the reflected sound picture. The cross sections are visualized on a screen or a print-out as a function of the distance from the nose opening.
Acoustic rhinometry is suitable for illustrating physiology of the nose mocous membrane, more specifically the thickness of this, for documenting diverting anatomy or for exposing of allergens and other material which irritates the respiratory passages, and for surveying the function of operative or medical treatment. The method can furthermore be used on children and even newborns.
The hitherto known measuring systems for acoustic rhinometry use a technique where a long rigid tube with a sound transducer such as a spark plug located in one end of the tube functions as a sound emitter, generating a planar acoustic wave propagating against the end of the tube which is terminated in a nose adaptation piece for connecting to the patients nostrils. A microphone located somewhere else in the tube measures the generated wave as well as a reflected signal. These rigid tubes normally have a diameter of 12-16 mm and a length of between 30 cm and 2 m.
The reflections in the lung cavities and the nose cavities following changes in the impedance (changes of cross sections) are sampled by the microphone in the tube and are transmitted to a signal processing unit, which calculates the cross sections of the cavities based on these.
Furthermore an equipment with a continuous acoustic broad band spectrum is manufactured and sold by the applicant (formerly S. R. Electronics ApS (DK)).
By means of the above-mentioned technique it is not possible to measure correctly the cross sections further in the respiratory passages of the patient than the rear end of the nose separation as the opposite nose cavity end at this location, whereby a cross section corresponding to the parallel connected acoustic impedance of the opposite nose cavity will be added to the cross section behind the nose separation.
For determining the length of the nose separation an endoscope, CT- or MR scanning, or a simple hook, which is inserted into the, nostril and is lead to the rear surface of the nose separation with the hook behind the edge, whereafter it is pulled back, has hitherto been used. When the hook abuts the rear surface of the nose separation, the examiner will at the nose opening mark the position on the shaft and the hook is retracted; the distance from the hook top to the marking indicated the length of the nose separation. The latter method is unpleasant for the patient and the first mentioned are expensive and implies some risk.
By using the apparatuses and methods for acoustic rhinometry described in the introduction, the length of the nose separation can be determined as the-distance where the sounds from one side of the nostril are identical as measured through the right and the left nostril, respectively (i.e., where the impedance by measuring in the right and the left nostril, respectively, are identical in the time-domain), but this method is implicit and the result depends of a subjective interpretation of the printed or shown curves. The measuring result is therefore connected with a large uncertainty.
It is an object of this invention to provide an apparatus which, in different configurations, can realize: measuring of cross sections of a patient""s respiratory passages, even beyond the termination of the nose separation, measuring of the total cross section of a patient""s right and left nose cavity in the same measurement, a simple and reliable measurement of the length of the patient""s nose separation, and a simple and reliable detecting of the opening (of) the patient""s Eustachian tube.
By means of the invention an apparatus is achieved which can emit sound signals in two directions along separate transmission tubes. At the sound emitter the two transmission tubes are located in line, which provides symmetrical impedance and reflection conditions.
By the fact that the apparatus hereby can send sound signals along two transmission tubes, a possibility for applying the sound signal (two) both nostrils of the patient is achieved, whereby both nose cavities takes part in the cross section measurement. This gives in one operation more valuable measurement and eliminates the harmful effect of the one nose cavity, which is not measured, acting as an acoustic shunt impedance (see above) on the second nose cavity and the cavity behind the rear edge of the nose separation.
The mentioned symmetrical impedance and transmission conditions ensures that the two part signals which propagates along respective nose cavities are sufficiently concordant for adding to a common signal at the nose separation rear edge without being distorted, which would deteriorate or destroy the measurement of the respiratory passages beyond the nose separation rear edge.
If the second transmission tube is releasable, the apparatus can still be used as the known apparatuses for rhinometry, for measuring through one nostril and for the mentioned measurement of the length of the nose separation and for detecting opening of the Eustachian tube.
With the features mentioned in claim 2 a simple and reliable connection to the patient""s nostril is achieved. If the microphones are located in the termination pieces, a considerable possibility for registration of the course of the cross section in each nostril and each nose cavity separately, still preserving the possibility of registration of the respiratory passages behind the termination of the nose separation.
With the features mentioned in claim 3 and 4 a particularly convenient configuration of the apparatus, when only the first transmission tube is used, having very limited risk of undesired reflections.
With the features mentioned in claim 5 a possibility is achieved for using the apparatus for measurement of the length of the nose separation.
With the features mentioned in claim 6 a possibility is achieved for using the apparatus for detecting opening of the Eustachian tube.
With the features mentioned in claim 7 an advantageous connection of the sound emitter to the transmission tubes is achieved.
It is a second objective of the invention to provide methods for the measurements and detections.
With the features mentioned in claim 8 it is achieved that the first acoustic signal propagates at the same time through both nostrils of the patient as two identical signals which therefore are identical at the rear edge of the nose separation, wherefore they will be added to a common well defined signal which propagates further into the patients respiratory passages and make rhinometry measurement possible in these respiratory passages located beyond the nose separation rear edge.
With the features mentioned in claim 9 a simplification of the apparatus and the computer software, which performs the signal analysis, is achieved.
With the features mentioned in claim 10 a more precise measurement is achieved, as the transmission tubes do not form part of the transmission path where the acoustic signals are changed by reflection a.o., and that the patients two nostrils and nose cavities are measured separately, whereby differences in the two sides can be seen and analyzed.
With the features mentioned in claim 11 a simple and reliable measurement of the length of the patients nose separation is achieved, without any discomfort.
With the features mentioned in claim 12 a very simple and reliable way of detecting whether a patients Eustachian tube is open or closed is achieved. As according to the invention only needs to be connected apparatus to the patient""s ears and nostrils, the detecting can be performed as the patient eats or drinks or swallows.
The apparatus may be constituted by a known apparatus, which has been provided with a supplementary tube and with a correspondingly revised signal processing software. The invention also relates to such supplementary equipment, which may be manufactured and marketed separate from the complete apparatus.
The invention is in the following be explained more detailed by means of embodiments with reference to the drawings on which the same references refer to corresponding parts on all figures.